Adjust includes to use <> instead of "", consistent with quickstart pages.

Right now, gtest documentation uses different #include syntax. The quickstart
pages (e.g., http://google.github.io/googletest/quickstart-bazel.html#create-and-run-a-binary) are checked in with `#include <gtest/gtest.h>` However, other
documentation (such as the primer) uses `#include "gtest/gtest.h"` (e.g.,
https://google.github.io/googletest/primer.html#writing-the-main-function).

PiperOrigin-RevId: 551878641
Change-Id: Iab93cc1da3ef4870a07b624071b75d6e9d3568c1

docs/gmock_for_dummies.md

@@ -164,7 +164,7 @@ follow:
 After the process, you should have something like:
 
 ```cpp
-#include "gmock/gmock.h"  // Brings in gMock.
+#include <gmock/gmock.h>  // Brings in gMock.
 
 class MockTurtle : public Turtle {
  public:
@@ -224,8 +224,8 @@ Here's an example:
 
 ```cpp
 #include "path/to/mock-turtle.h"
-#include "gmock/gmock.h"
-#include "gtest/gtest.h"
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
 
 using ::testing::AtLeast;                         // #1